Improvement in slide-valves for steam-engines



o. M. MILLER. i Slide-Valve for Steam-Engines.

No. 206,398. Patented July 30,1878.

7 .Z'aewsecr f Jaffa/fof N. PETERS, FHOTOL|TMOGRAPHEH, WASHINGTON, D c.

I, IASSIUS M. MILLER, OF CANTON, OHIO, ASSIGNOR OF ONE-HALF IllS ll-lGlil'l UNITED; STATES PATENT lcanton.

TO C. AULTVMAN S: CO., OF SAME PLACE.

IM PRovr-:M ENT INV SLIDE-VALVES Foa sTEAMgl-:Nel NES.

Spmmon fom-ling Durf OVLOCVS Pcnt N 206,395', dnll July 30, 1575; appli-cation tiled Diny 20, 1878.

To all fzrhom vit may concern: Y

Be it known that I, Cassius M. MILLER., of Canton, in the county of Stark and State of Ohio, have invented certain new and useful Improvements in Slide-Valves for Steam- Engines; and I do hereby declare the following to be a full and exact description ofthe same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure 1 is a longitudinal vertical section of my invention, and Fig. 2 a transverse section of the slide-valve detached.

Similar letters of reference in the several figures denote the same parts.

My invention relates to that class of valves in which a variable cut-off is effected by means of a slide valve or valves working within the body of the main valve 5 and it consists in making the internal cut-off valve or valves to fit closely, like pistons, in the passage in which they slide, and in extending the steam-ports nearly or quite around such passage, so that they can be made very narrow, and the valves caused to cut off the steam almost instantaneously.

It also consists in certain minor details of construction, which will be hereinafter more fully described.

In the drawings, A represents a common double slide-valve, having steam-ports S S', a-nd operating in connection with the ordinary valve-seat, having the usual steam and exhaust passages. Through the back of the valve, longitudinally, and parallel to its face, is provided a straight passage, G, preferably cylindrical in shape, through which the live steam enters the ports S and S' alternately, and passes to the steam-cylinder. The cutofi' valves D D are arranged within the passage C in the usual manner, except that they are made in the form of pistons, tting the passage C closely at their sides and top, as well as ou their under surface. The steam ports S S are extended nearly or quite around the cylindrical passage C, so as to take steam on all sides thereof, whereby their mouths may be made in the form ot' a narrow slit, which will be almost instantaneouslyopened or closed by the movement of the cut-off valves. Back of their mouths, within the bodyof the valve, these ports or steam-passages are enlarged or chambered out, as shown at t, to give a freer movement to the steam. The cut-off valves are adjusted and operated in the usual man-r ner.

It will be seen that by this construction the cut-oft' valves will not only operate more quickly and effectually, but will themselves be more completely balanced than as heretofore constructed. VAt the back or upper side of the valve a large opening, E, is made in the cover of the steam-chest F, and a sliding hollow cylinder, G, is closely fitted therein, having a flat plate, G', at its lower end, which rests lightly upon and is closely fitted to the back of the valve. rIhe plate G is provided with a large central opening, g, and with projecting corners or edges g g', which latter serve, by the pressure of the surrounding steam, to hold the plate in contact with the valve and the valve properly to its seat. The upper end of the hollow cylinder G tits into a collar, f, upon the steam-chest cover, and is provided with a packing, m, secured and adj usted by a gland, n, by means of a screw-cap, l1., as will be readily understood.

A small air-pipe, I, provided with a cock, i, serves to place the interior of the cylinder G in communication with the open air at the will of the engineer. This air-pipe may be arranged within a hollow set-screw, J, provided for the purpose of enabling the engineer to set the plate Gl against the back of the valve whenever it may for any purpose be desirable to do so.

It will be seen that by this construct-ion the cylinder G and its plate G completely exclude the steam from alarge area on the back of the valve, which area can at will be put in direct commiuiication with the open air, thus completely relieving the valve of a large portion of the steam-pressure, and yet retaining on the projecting parts of the plate around the hollow center a sufficient steam-pressure to hold the plate in close contact with the valve, and the valve at all times properly to its work.

The surfaces in sliding contact are all to be made as smooth and closely fitting as possible, in order to diminish frictionV and rwear and secure steam-tight connections.

The lower edge of the gland n is to be made V-shaped, as shown, in order that it may expand the soft hemp packing m into close and constant contact with the proximate surfaces, and thus insure a perfect-ly steam-tight joint.

Having thus described 1n y invention, I claim as new- 1. The main slide-Valve, having ports S S and a substantially-cylindrical passage, C, in combination with piston cut-oft' valves D D, closely tting the cylindrical passage, substantially as described.

2. The main slide-valve, having the substantially-cylindrical passage (l, and having ports S S', the mouths of which extend in a narrcm' slit nearly or quite around the Walls Witnesses:

JNO. M. WELLS, ORLANDO RANK. 

